We will develop optimal techniques to study the growth and treatment of clonogenic cells from malignant brain tumors. We will utilize further methods to characterize tumor cells and normal cells, and the clonogenic tumor cell hierarchy. We will evaluate the representative nature of the cells dissociated from biopsies and the influence of tumor specimen selection. Optimal means for growing and treating brain tumor cells will be developed with an emphasis on those conditions that simulate mostly the in vivo environment and physiologic drug exposure. Methods of statistical analysis will be developed to analyze cell survival, evaluate error, and provide directions to improve assay methodology. A panel of tumores will be treated with chemotherapeutic agents with known or potential utility to treat patients; an agent's tumor specificity will be evaluated by a comparison with activity against normal glioma cell and non-tumor cells from the same patient. We will compare the results of in vitro clonogenic cell assays to in vivo antitumor responses to define the limitations of and to improve the culture assay system. Finally, we will develop further and validate a bone marrow CFU-GM assay to study selected drugs and drug combinations which have demonstrated efficacy in tumor culture systems.